As a conventional type exhaust gas purification device, an exhaust gas purification device of an internal combustion engine comprising an NOx holding material arranged in an exhaust passage of the internal combustion engine, ozone introducing means for introducing ozone to an exhaust passage arranged in an exhaust passage on the upstream side from the NOx holding material, a three-way catalyst arranged in an exhaust passage on the downstream side from the NOx holding material, a selective catalytic reduction catalyst that is prepared to provide the activity at a lower temperature than the three-way catalyst arranged on the upstream side from the three-way catalyst, and oxygen introducing means for introducing oxygen to an exhaust gas on the upstream side from the selective catalytic reduction catalyst arranged on the upstream side from the selective catalytic reduction catalyst is disclosed (e.g. Japanese Unexamined Patent Application Publication No. 2008-163881).
The exhaust gas purification device of an internal combustion engine thus configured is provided with a function of purification by reacting a NOx and a hydrocarbon (HC) under lean atmosphere, since a selective catalytic reduction catalyst thereof is prepared so as to be activated at a lower temperature than a three-way catalyst. Consequently, a NOx that fails to be absorbed or trapped in a NOx holding material before the three-way catalyst is activated can be efficiently purified to improve NOx purification performance. In addition, since the selective catalytic reduction catalyst is arranged on the upstream side from the three-way catalyst, the activity of the selective catalytic reduction catalyst can be swiftly provided before cold start of the internal combustion engine. After the activity of the three-way catalyst is provided to some extent, NOx that cannot be purified by the selective catalytic reduction catalyst can be purified by the three-way catalyst. As a result, NOx purification performance can be improved.